1. Technical Field
This invention relates to active noise control, and more specifically to automatic selection of speaker combinations to produce destructively interfering sound waves.
2. Related Art
Active noise control may be used to generate sound waves or “anti noise” that destructively interferes with undesired sound waves. The destructively interfering sound waves may be produced through a loudspeaker to combine with the undesired sound waves in an attempt to cancel the undesired noise. Combination of the destructively interfering sound waves and the undesired sound waves can eliminate or minimize perception of the undesired sound waves by one or more listeners within a listening space.
An active noise control system generally includes one or more microphones to detect sound within an area that is targeted for destructive interference. The detected sound is used as a feedback error signal. The error signal is used to adjust an adaptive filter included in the active noise control system. The filter generates an anti-noise signal used to create destructively interfering sound waves through at least one speaker. The filter is adjusted to adjust the destructively interfering sound waves in an effort to optimize cancellation within the area. In systems having multiple speakers, a fixed number of speakers may be used to generate anti-noise. However, some speakers may not be used to generate anti-noise but in some situations may be more suitable than speakers being used due to source location and characteristics of the undesired sound. In addition, the source location and characteristics of the undesired sound may change over the course of time. Therefore, a need exists to adaptively select speakers being used to produce destructively-interfering sound waves.